Asking for a method used in data mining(especially for blog webpages)

recently I attended a talk on data-mining,and I missed some points by the lecturer,which is about a technique used on data-mining,and which is especially useful for blog webpages. I think I sort of remembered the term is named as "td/tdf" something,but really not sure. I googled for this for a while,still have no result.

It would be great if you could point o开发者_JAVA百科ut what this technique is,since I want to look further into this topic.

Thanks a lot.

I think maybe you mean temporal difference learning.

Edit
As mentioned in the comments, actual answer is Term Frequency / Inverse Document Frequency.